What is the washed coffee process?

The washed process — also called wet processing — is a post-harvest method that mechanically removes the cherry's pulp, ferments off the sticky mucilage around the bean, then rinses and dries the coffee. It delivers a clean, bright, transparent cup that lets variety and terroir speak clearly.

The sequence opens with hydraulic sorting: floating cherries (unripe or damaged) are skimmed off. Ripe cherries then move through a disk or drum depulper, which strips the red skin and most of the pulp. Left behind are the paired beans, still coated in a sugary, pectin-rich gelatinous layer — the mucilage. That layer must be removed before the bean can dry cleanly, and this is where controlled fermentation enters the picture.

Fermentation takes place in open or closed tanks, typically made of concrete or stainless steel, sometimes with added water and sometimes dry. It lasts 12 to 72 hours on average, stretching up to 96 hours in the high, cool altitudes of Kenya or Rwanda. The microbial community doing the work — Saccharomyces cerevisiae yeasts, Lactobacillus and Leuconostoc lactic acid bacteria, Acetobacter in the later phase — produces organic acids (lactic, acetic, citric) that shape the sensory profile. Producers monitor pH (targeting 4.0-4.5 by the end) and temperature; overshooting tips the lot toward vinegary or phenolic defects.

Once the mucilage has broken down, the beans are rinsed in washing channels that also sort by density, then laid out on patios, raised African beds, or in mechanical dryers. Drying targets 10-12 % residual moisture and takes 6 to 20 days. The environmental footprint is real: the washed process traditionally uses 40 to 150 litres of water per kilo of green coffee, which has pushed cooperatives in Kenya, Costa Rica and Rwanda to invest in low-water pulpers and closed-loop water recycling. In the cup, the washed signature is unmistakable: vivid acidity, medium body, floral or citrus notes, and a clear read on terroir — exactly what Scandinavian, Brussels-based and Ghent-based roasters have built the modern specialty standard upon.

Stages of the washed process